change language JOptionPane

I have a program entirely in English, and I post in dialogs with the methods of JOptionPane.
But I found that the buttons appear in French, so I OUI/NON or OK/ANNULER instead of YES / NO and OK / CANCEL.

You can switch your entire Locale to English by calling Locale.setDefault(Locale.ENGLISH) at the start of your application. Please note that this also affects date/time and number parsing and formatting.